Abrasion testing machine



J 1952) e. F. BLACKBURN ETAL 8 3 ABRASION TESTING MACHINE Filed July 22, 1949 GEORGE Ff BLACKBURN EDWIN R. PAUL Patented Jan. 15, 1952 ABRASION TESTING MACHINE George F. Blackburn, Montgomery County, Md., and Edwin R. Paul, Washington, D. C.

Application July 22, 1949, Serial No. 106,266

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 3 Claims.

This invention relates to abrasion testing machines and in particular to a machine for testing the resistance-to abrasion oi the insulation or covering on electric wires and cables.

At present, abrasion testing machines employ abrasive wheels or sharp edges to wear away or penetrate the insulation or covering on cables. It has been found that knife edges rapidly become dull and abrasive Wheels become clogged with the material as it is abraded away. In other machines, the load applied to the specimen wire is variable with the tension applied to the wire to hold it or draw it over the abrading surface.

The present invention has for its object to provide a machine in which the load applied to the abrading surface may be held normal and constant at any desired value.

Another object of the invention is to provide a machine in which a new and unused section of an abrading surface may be used for each test.

Another object of the invention is to provide a machine which may be used to abrade either round, rectangular, or other shaped electric cables.

Other objects and advantages of the invention will hereinafter become more fully apparent from the following description of the annexed drawings, which illustrate preferred embodiments, and wherein:

Fig. 1 shows an elevational view of the invention.

Fig. 2 shows a view in elevation of a portion of the invention.

Fig. 3 shows a partial View partly in section of another embodiment of the invention, and

Fig. 4. shows a view in section of a portion of the invention taken on line 4-4 of Fig. 1.

Referring in more particular to the drawing, in Fig. 1, a base Iii has secured to it a support it for holding electric motor [2 and reduction gear unit 13.. Also secured to base I!) is post is having at its upper end a work plate I5 secured by set screws I5 and supporting a dial indicator gauge It by means of off-set bracket t? and adjustable clamp l8, as seen in Fig. 2.

Positioned between the work plate 15 and the gauge H5 is a vertically movable post it pivotally connected to off-set bracket I! by arms 2i and pivot pins 22. Weight 23 is attached to arm 2! and provides downward pressure to post 19.

Post 19 has at its lower end press plate 24 secured to it by welding or other conventional means, and a channel 25 in the press plate 24 serves to center a round electric cable 26.

In the embodiment shown in Fig. 3, press-plate 24 is loosely joined to post I9 by ,a ball and socket joint 25' in order that other-shaped cables 26 may be abraded.

Work plate I5 is adjustable on post l4 bymeans of set screws 15 and has guides 21 to guide the abrasive strip 28 as it is pulled by rollers 29 and 36 from reel 3! to take up reel 32, which are supported by posts 33 and 34 having clamps 35 and 36 at their upper ends respectively, as shown in detail in Fig. 4.

Heels 3i and 32 have pulleys 31 and 38 attached to their sides and are connected by belt 39. It will be seen that owing to the larger pulley 3'! driving the smaller one 38, an amount of slippage is needed in order to apply no more than the proper tension to the abrasive strip 28 as it is wound on the take-up reel 32.

Pin 46 of the gauge it rests on the post l9 and actuates the gauge IE to indicate the amount of insulation abraded from the wire 26 or 25'. A pair of clamps 4! and 42 are fixed to post 19 and bracket ll respectively and have contacts 43 to complete an electrical circuit when a desired amount of insulation has been worn away.

Set screws l5 may be adjusted in order that the work plate [5 can be positioned on post 14 so that a fresh part of the abrasive strip 28 may be used for each rerun of the strip.

In operation, the wire 26 is held by clamps 35 and 36 and with the rollers 29 and 30 pulling the abrasive strip 28, the number of turns of the take-up reel 32 may be counted or recorded on a counter 44, and the contacts 43 may be in a circuit including a relay 45 to actuate a signal, or to stop the motor l2 by actuating switch 46 in the motor circuit to an open position, as shown in Fig. 1. A control switch 41 is shown in the motor circuit for manual operation.

It should be understood, of course, that the foregoing disclosure relates to only a preferred embodiment (or embodiments) of the invention and that numerous modifications or alterations may be made therein without departing from the spirit and the scope of the invention as set forth in the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. An abrasion testing machine for insulated wires comprising a base, a pair of supports for reels secured thereon, clamping means one on each of said supports adapted to secure a Wire therebetween, a reel on each support, a laterally movable anvil secured to said base over which said wire is held, an abrasive tape wound on and between said reels and passing over said anvil under said wire, a motor and reduction gear on said base drivably connected to a pair of friction rollers having said tape drivably positioned therebetween, driving means connecting the one of said reels driven by the movement of said tape therefrom to the other or take-up reel, movable holding means on said base positioned over said anvil adapted to press said wire against said tape on said anvil, tape guiding means on said anvil, means for moving said anvil and said tape-guiding means laterally prior to a test so as to present an unused portion of said tape to said wire for successive tests, indicating means on said base for measuring the movement of said holding means toward said anvil resulting from the abrasion and removal of insulation from said wire, and contact means operable by the resultant movement of said holding means to deenergize said motor when a predetermined amount of insulation has been removed.

2. The device as set forth in claim 1 in which REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 895,980 Derihon Aug. 11, 1908 1,632,591 Dennis June 14, 1927 1,881,031 Rounsevelle Oct. 4, 1932 2,292,577 Mahannah Aug. 11, 1942 2,373,115 Graves Apr. 10, 1945 FOREIGN PATENTS Number Country Date 519,711 Great Britain Apr. 3, 1940 

